The marriage to a commoner of the Duke's other brother, the Duke of Cumberland, led to the passing of the Royal Marriages Act 1772, which required all the descendants of George II to seek the sovereign's approval before marriage. It was only in September 1772, five months after the passage of the Act, that the King became aware of Prince William's marriage to Maria. As the Act's provisions could not be applied retroactively, Maria and the Duke's marriage was considered valid. Due, however, to the anger of her brother-in-law at the marriage, she was never received at court.

Princess Caroline died aged nine months following a smallpox inoculation, intended to protect her from the disease.[1]